Organopolysiloxane materials having a cone penetration between about 100 and 350 (10.sup.-1 mm) (ASTM No. D217-68) and an ultimate elongation of at least 100% (ASTM No. D638-80) contain a mixture of crosslinked and uncrosslinked organopolysiloxane. The uncrosslinked organopolysiloxane oil may constitute from about 10% to about 90% by weight of the mixture but may be between 25 and about 75% by weight and more usually may be between about 30% to about 70% by weight These materials are useful as sealants and for forming protective covers over various substrates to protect the substrates from environmental conditions, moisture, or other undesirable elements. The various properties of these materials such as the elasticity, conformability, self-healing properties, elongation and other aspects make these materials very attractive as sealants for various substrates. In particular these materials are attractive because they can be repeatedly removed from and replaced on the various substrates without substantial loss of the adhesion to the substrate due to the surface tackiness of the organopolysiloxane material.
These materials generally have a very high surface tackiness. However, due to the uncrosslinked oil content of the mixture it is difficult to adhere the mixture preferentially to one surface, such as a support member, as opposed to another surface, such as a substrate, so that the organopolysiloxane material may be applied to a substrate and then removed from the substrate by adhesion to the support member.
In order to be useful in many applications, these organopolysiloxane materials must be used in combination with a support or container by which the material may be handled. These types of materials have been used in various containers and cast in a flexible matrix and used with release papers as illustrated by copending applications U.S. Ser. No. 434,011 filed Oct. 12, 1982; U.S. Ser. No. 507,433 filed June 23, 1983; U.S. Ser. No. 507,435 filed June 23, 1983; and U.S. Ser. No. 688,849 filed Jan. 4, 1985; which are incorporated herein by reference. In these applications the organopolysiloxane material is generally held to the container or support by the mechanical configuration thereof or in the case of release papers the material is placed between two substrates without the intent of removal and reuse.
It is desirable to have these organopolysiloxane materials adhere to a support material, such as a polymeric sheet or tape, with a force greater than the adhesive force with which it bonds to a substrate through surface tackiness or other mechanism. In general it is desirable to have these organopolysiloxane materials bonded to a support with a bond strength greater than the cohesive strength of the organopolysiloxane material itself.
Apparently due to the uncrosslinked oil content of these organopolysiloxane material attempts to bond the material to a support have met with limited success. In copending application U.S. Ser. No. 560,344 filed Dec. 12, 1983, it is disclosed that neoprene contact adhesive will bond a support to urethane materials having similar properties and characteristics including an uncrosslinked oil content. It has been found that contact adhesives will not bond the organopolysiloxane materials of this invention to supports. In copending application U.S. Ser. No. 711,119 filed Mar. 12, 1985, it is disclosed that elastomeric sealants having properties and characteristics similar to the organopolysiloxane materials of this invention will bond to certain porous polymeric support materials. In copending application U.S. Ser. No. 730,404 filed of even date herewith, it is disclosed that organopolysiloxane materials of this invention may be bonded to a support material with a silicone pressure sensitive adhesive.
It is believed that due to the uncrosslinked organopolysiloxane oil content present in the materials of this invention, it is completely unpredictable and unforeseen how these materials can be bonded to a support with a bond strength greater than the cohesive strength of the organopolysiloxane material itself.
Radiation grafting of various materials such as hard rubber is known in the art as illustrated by U.S. Pat. No. 3,179,546 to Fischer, U.S. Pat. No. 3,669,796 to Hall et al. and U.S. Pat. No. 3,939,049 to Ratner.
It is an object of this invention to bond such organopolysiloxane mixtures to polymeric support to thereby render the combination suitable for use as a tape or other protective article.